So for about a year the Accent has been making this awful noise that seems to be backfiring or an attempt to backfire through the intake when the car is shut off. The noise varies in volume from barely audible to drawing the attention of people quite a ways off in a crowded parking lot. I've had it in several times the last few months for service because I'm just plain getting tired of hearing it but the dealership, as of this posting, hasn't been able to determine the cause or repair it. I've made multiple trips because in order to service it under warranty they required that I remove my aftermarket intake header and exhaust. Of course the sound is much more audible when it's opened up with the intake and exhaust than it is with the more restrictive stock components installed. My question to everyone is have you ever heard anything like this before in any car or in a Hyundai of any type? I'm getting desperate to get this solved as it doesn't seem to necessarily be causing any trouble but at the same time isn't "normal" otherwise they'd all do it. Thanks in advance.

-Trey

 

Hmmm....it could be a bad MAF. Also, check your hoses between the intake and TB. If there are any holes in it, that could also be whats causing it (vacuum leaks). I would also check the voltage at the MAF as well.

Last but not least...double check your timing. Thats probably a least likely case, but that can be something that would cause the backfire if it was off a little.

 

No MAF, they're MAP based.

 

My guess is that the timing belt either jumped time or if it's been replaced was installed one tooth off.

 

I have not replaced the timing belt yet as it's just now time. I'd thought about timing but wondered how with electronically controlled timing that was possible so I'm glad you said that Floyd.

 

If it's time to replace the timing belt, I would just get that done (at the dealership) and they'll install the new one correctly. If that doesn't fix it, you could have an intake valve that's not seating quite properly for one reason or another, maybe a weak or broken valve spring for one example.

 

Supposedly I'm going to be meeting with the owner of the dealership and their rep from Hyundai this morning. We'll see if I actually get a return phone call.

 

Good luck!

 

Full story coming soon but in the interim feel free to check out the noise and tell me what you think. For reference, the microphone was placed inside the stock airbox to minimize outside noise pollution. http://dl.getdropbox.com/u/2044600/intake.mp3

 

Okay, that might be normal. It has a longer delay than mine does, but sometimes mine will make a similar noise right after shutting the engine off. I think it's the engine bouncing back slightly off of a cushion of compressed air when shutting off.